Preparation Of Porous Manganese - Based Oxide By Chemical Impregnation And Its Electrocatalytic Properties

Hydrogen is one of the clean energy in the world, and photoelectrically splitting of water to produce H2is an ideal clean energy technology, efficient electric catalyst is one of the keys to implement this technology. Water splitting process includes two half-reaction, oxygen evolution reaction (OER) of anode and hydrogen evolution reaction (HER) of cathode. For oxygen evolution reaction, noble metal Ru, Ir and its oxide RuO2, highest IrO2is currently best catalysts. But these materials still exist many limitations, such as unstable in alkaline medium, expensive and scarcity. So the development of non-noble metal catalysts with high catalytic activity, good stability, low cost and abundance is of great significance. In the past few decades, the scientific community has found some transition metals and oxides can also exhibit efficient catalytic activity for OER.In this article, FeOx/CFP OER catalyst was fabricated by simple chemical impregnation method, which use KMnO4and FeCl3as sources of Mn and Fe, respectively, and the Mn and Fe oxides were in situ formed on the carbon fiber paper (CFP). SEM, EDS, XPS, XRD and BET were used to characterize the morphology, chemical elements, valence, crystal structure and specific surface area of the catalysts. Results confirmed that the materials loading on the CFP were a mixture of MnO2and Fe2O3.Cyclic voltammetry (CV), chronoamperometry (CP) and linear sweep voltammetry (LSV) were adopted to studing the OER catalytic performance. When the potential of1.8V (vs. RHE), oxygen evolution current density was17.72mAcm-2; To reach a current density of5mA cm-2, oxygen evolution potential is469mV; OER onset overpotential was393mV; Tafel slope of65mV dec-1; conducted at voltage of1.767V (vs RHE) for6000s, current density stable at about11.08mAcm-2. Mn-FeOx/CFP OER catalytic parameters is better than that of Pt electrode.Respectively investigates the influence of KMnO4concentration, pH, molar ratio of FeCl3, dipping time and drying methods of Mn-FeOx/CFP on the catalytic activity of catalysts. The results are as follows:(1) When the precursor solution concentration was0.1mM, catalyst performance is low, the amount metal oxide load on the fiber is too little; And when the concentration was5mM, the electrical conductivity of the catalyst decreased, thus reducing the catalytic activity.(2) the change of the precursor solution pH value, apparent effect on catalyst performance.Under acid condition of Mn-FeOx/CFP significantly better than in alkaline conditions.(3) when the molar ratio of KMnO4and FeCl3in precursor solution is different, the difference appered in the obtained catalysts. When only the KMnO4or FeCl3was in solution, only MnO2or Fe2O3loaded on the CFP, MnOx/CFP and FeOx/CFP catalyst activity is low. And when the solution is mixed solution, exhibited excellent catalytic performance.(4) different impregnation time of catalyst, the catalytic properties have some difference. Mn-FeOx/CFP obtained by10min impregnating, the performance is worst, with the extension of dipping time, the catalytic activity increased, when the dipping time is48h, activity decreases.(5) the length of the drying time have little impact on the catalyst activity, high temperature leaded a worse catalytic activity when compared with other condition.